Overview and Reasons for Canine Blood Transfusions
Canine blood transfusion is usually indicated in acute cases of blood cell breakdown or when there is a severe loss of blood. Similarly, dogs with acute or chronic anemia (below normal level of red blood cells), due to any cause can require a blood transfusion. Some dogs may not require whole blood, but a part of the blood, such as plasma or platelets.
Whole blood transfusion is usually not needed; preferably a part of the blood that is required for the particular diagnosis should be transfused. For example, if the treatment objective is to only improve the oxygen-carrying capability of blood, red blood cells can be transfused instead of whole blood. Platelets are usually not required in blood transfusions for hemorrhage, as the number of platelets naturally increases. Similarly, only crystalloid colloid solutions, combined with packed red blood cells are required in some transfusions.
Defining the treatment required and then limiting the transfusion to the indicated part of the blood not only helps to reduce associated risks, but also helps to define the requirements of the canine blood transfusion.
Canine blood transfusions can be distributed into three different parts: collection, storage and transfusion. Each step requires that specific protocols be followed before heading towards the next step.
Minimizing the Risks of Canine Blood Collection
Canine blood for transfusion must be collected from healthy, disease free and vaccinated donors. The diversity of blood groups in dogs makes it hard to select appropriate donors, thus blood grouping, typing or cross matching should be done when possible to reduce the chance of complications, such as acute hemolysis (the destruction of dissolution of red blood cells, with the subsequent release of hemoglobin) and incompatibility, which can then turn into a severe medical emergency.
Canine Blood Storage
Collected blood must be stored in an aseptic (sterile) environment. Citrate phosphate dextrose adenine (CPDA-1) is the choice anti-coagulant for prolonged storage. Vacuum bags containing the appropriate amounts of coagulant are preferable over vacuum bottles, as the degree of damage is lower in bags.
Heparin is another common anti-coagulant, although it is not recommended for dogs as it activates platelets due to its longer half-life in recipients.
Collected blood, mixed with CDPA–1, can be stored at 4 Degrees Celsius for 3 weeks. Plasma can be removed from the blood for prolonged storage. Plasma should be frozen at 20 to 30 Degrees Celsius (68 degrees to 86 degrees Fahrenheit) within 6 hours of separation, which will ensure quality. The blood is usable for 1 year.
Types of Canine Blood Transfusions
Blood can be transfused as a whole or parts, as required by the condition being treated. Examples are anemia and hemostatic (red blood cell) disorders. These products are stored in different forms and in different environments and should only be administered as directed.
Canine Whole Blood Transfusion
Whole blood transfusion is indicated in hemorrhage or hypovolemia (blood circulation deficiency). Dogs with more than a 30% loss of blood should only be transfused with whole blood. Whole blood in most conditions cannot be administered due to anti-coagulant dependency and availability and storage restrictions, i.e. whole blood can only be stored for 4 weeks.
Canine Plasma Transfusion
Plasma is usually required in cases of deficiency in multiple clotting factors and hypoproteinemia (abnormally low levels of protein in the blood), as stored plasma contains all clotting factors except platelets. Plasma can be stored for 0.5–1 year at 70 Degrees Celsius (158 degrees Fahrenheit). In case blood is not available, plasma can also be used to control hypovolemia (diminished volume of circulating blood).
Packed Red Cells Transfusion
Packed red blood cells are used mostly for the treatment of anemia. These are re-suspended in 0.9% NaCl solution prior to administration which reduces their viscosity. Packed red cells can be refrigerated and used for only 3 weeks after collection and separation.
Risks of Canine Blood Transfusion
Acute hemolysis (break down of red blood cells) is the most common risk associated with a canine blood transfusion. It is less frequent in dogs, but is suspected in cases where repeated blood transfusions are required. This may occur because of a significant number of anti-bodies preformed in the recipient, which is more common in repeatedly transfused dogs.
Other risks such as contamination, sepsis, hypocalcemia and hypervolemia are possible with canine blood transfusion, although they can sometimes be due to carelessness.
Some dogs may show signs of vomiting, fever or illness after transfusion, which should be monitored closely, as these can indicate illness or an unwanted element in the transfused blood, such as bacteria or contamination.
C. Bowden, et. all. “Text Book of Veterinary Medical Nursing” (Elsevier Health Sciences. 2003)